JetpackNav3 Sample Application

This is a sample Android application demonstrating the usage of Jetpack Navigation 3 (Nav3) with Jetpack Compose.

Features

• Jetpack Navigation 3: Uses the latest experimental navigation library from Google.
• Type-Safe Navigation: Leverages Kotlin Serialization for type-safe navigation keys (Home, Profile, FlowerDetail).
• Jetpack Compose: Built entirely using modern Compose UI.
• Backstack Management: Demonstrates using SnapshotStateList and mutableStateListOf for flexible, observable navigation state across multiple tabs.
• Adaptive Layouts: Implements a custom SceneStrategy for List-Detail views on large screens.

Project Structure

• MainActivity.kt: Contains the entry point and navigation logic using NavDisplay.
• AppNavBackStack.kt: Manages multiple tab-specific backstacks using observable state.
• NavKey: Navigation destinations are defined as @Serializable data objects.
• EntryProvider: Uses the entryProvider DSL to map navigation keys to Composable screens.
• SceneStrategy: Custom strategy (ListDetailSceneStrategy) to handle adaptive multi-pane layouts.

Implementation Details

Architectural Decorators

The project utilizes rememberSaveableStateHolderNavEntryDecorator and rememberViewModelStoreNavEntryDecorator to ensure that screen state is saved and ViewModels are properly scoped to their respective navigation entries.

Adaptive Scenes

By leveraging the SceneStrategy API, the app can display two active destinations simultaneously (e.g., a list and a detail view) when sufficient screen width is available, while automatically reverting to a single-pane flow on smaller devices.

TODO & Future Enhancements

• Persistent: Make it survivable through configuration changes and system-initiated process death
• CompositionLocal for Backstack: Implement a custom NavEntryDecorator to provide the backstack via CompositionLocal, eliminating prop-drilling for navigation actions in deep hierarchies.
• Synthetic Backstacks for Deep Linking: Develop a utility to parse incoming URLs/Intents and generate logical backstack sequences (e.g., [Home, Profile] instead of just [Profile]) to ensure intuitive back navigation.
• Metadata-Driven Transitions: Utilize the Metadata DSL (anticipated in version 1.1) to define type-safe, declarative animations per NavKey type.
• Kotlin Multiplatform (KMP) Readiness: Move core navigation logic and NavKey definitions to a common KMP module to enable shared navigation state across Android, iOS, and Desktop.

Getting Started

1. Ensure you have Android Studio installed.
2. The project uses Kotlin 2.1.0 and Jetpack Compose.
3. It requires the kotlin-serialization plugin to be applied in build.gradle.kts.

Dependencies

Key dependencies include:

• androidx.navigation3:navigation3-ui
• androidx.navigation3:navigation3-runtime
• androidx.lifecycle:lifecycle-viewmodel-navigation3
• androidx.compose.material3.adaptive:adaptive
• org.jetbrains.kotlinx:kotlinx-serialization-json